In the manufacturing environment, fluid power systems are typically used to automate machines, transport materials, and/or control processes. Such systems typically include a plurality of actuators that are operatively connected to valves. The actuators are connected to the valves by a series of tubing and fittings. The valves may be controlled by a number of devices such as microprocessors or programmable logic controllers or through analog control circuits. The fluid power systems typically run on compressed fluid such as air or hydraulic oil.
During the use of fluid power components, it is almost inevitable that leakage will occur somewhere in the system. One common area of leakage is between the actuators and the valves. Such leakage can occur by failure of the tubing, for example, by exposure to corrosive substances, abrasion as the tubing moves along with an actuator, or the tubing may inadvertently being pinched during the manufacturing process. In addition, fittings which attach the tubing to the valves and actuators can become loose and permit leakage from the valve ports and/or cylinder ports.
Such leakage is undesirable and can have various deleterious effects. For example, in pneumatic systems the pressurized air is provided by compressors which are expensive to operate. Accordingly, even small leaks in a system left unattended, can lead to significant increase in operating costs for the system. In addition, when pneumatic systems are used in environments where the condition of the ambient air is required to stay clean, unwanted air leakage can also lead to contamination and maintenance issues. In the case of hydraulic systems, leaks will spill hydraulic oil out of the lines leading to contamination of the surrounding area. While these leaks may be more easy to identify than in a pneumatic system, if left untreated, they can create significant maintenance issues. In addition, leaks can affect actuator performance and the overall performance of the equipment. Accordingly, it is desirable to eliminate and detect the presence of leaks as soon as possible.
Leaks are typically diagnosed in pneumatic systems by listening for the sound of hissing air and by periodically inspecting tubes and tightening fittings which may be susceptible to loosening. Such inspections are time consuming and may be difficult to perform in a noisy industrial environment. Hydraulic system leaks which result in the spillage of hydraulic oil can be seen, however, such leaks would only be uncovered if they are in an area where an operator can view the leak. Such inspection methods will often miss small leaks and prevent maintenance from being done early on in a leakage event before any problems occur.
It is known in the prior art to use various sensors in order to detect leaks in a fluid power system. Such methods include using a multitude of sensors, for example, one for each actuator, in order to see changes in air flow for a particular actuator. Methods relying on a multitude of sensors, however, require significant processing power and increase complexity.
Accordingly, it would be desirable to provide a method and apparatus for detecting leakage in a fluid power system in an automated manner without the need for excessive components.